What's the best swimming aid for toddlers?

[Ames19]

Been taking my 2.5 year old swimming a lot since everything had reopened.

I've got him one of them swim vests but he doesn't seem to stay afloat with it, he just kind of sinks.

Wondering if anyone can recommended anything?

Tia x

Pool noodle.

Honestly anything else is a waste if time and will hinder learning to swim.

Supervision and a pool noodle is safest and most effective.

A shark fin. Leaves their arms free and they don't know they're wearing it.